GB678394A - Control systems for internal combustion engines - Google Patents

Abstract

678,394. Fluid-pressure servomotor-control systems. BENDIX AVIATION CORPORATION. April 26, 1948 [June 6, 1947], No. 1760/48. Divided out of 678,364 and addition to 678,361. Class 135. An aircraft engine control system as in the parent Specification, but in which the cruise override and propeller control mechanisms are omitted and the supercharger is driven through three hydraulic couplings instead of two, has improved combined means for increasing the intake pressure permissible during operation of an anti-detonant injection system and for reducing the permissible pressure with increase of altitude. As shown, movement of an arm 306 connected to the pressure selecting mechanism in a direction to increase the pressure selection is limited by a plunger 304 reciprocable in a guide 305 by a lever 301 which is connected to plungers 302, 303. Pistons 316, 317, associated with the plungers and urged upwardly by springs, have their upper surfaces communicating, though restrictions 308, 311, 312, with a pressure supply conduit 307. An outlet 315 is normally opened by an electromagnetically-operated valve (not shown) so that insufficient pressure exists above the pistons 316, 317 to balance their spring loadings. The pistons thus take up the positions shown, limited by adjustable stops 370, 371, but during operation of the anti-detonant system, the electromagnetically-operated valve is closed and pressure builds up above the pistons and allows the plunger 304 to recede from the arm 306. A further piston 327, loaded by a spring 328 and provided with a hollow stem 329, is subjected on its lower face to the pressure in a passage 313 which pressure has access to the interior of the hollow stem and is regulated by a leak-off valve 333 positioned by a bellows assembly comprising an evacuated spring- loaded bellows 337 and a bellows 338 whose interior is subjected to atmospheric pressure. Thus the plunger 302 and, therefore, the plunger 304, are moved in response to variations in atmospheric pressure to limit the permissible selected pressure in accordance with altitude.